Bit for rock drilling



Sept. 2, 1950 s. A. KNQWLES BIT FOR ROCK DRILLING Filed May 21, 1948 fly].

IN V EN TOR. SQ/asA/fmowiw IIIIII 1 1 Patented Sept. 12, 1950 PAT ENT OFFICE l :l a ass/22,0475

I nireonnocn-narnmho silas.-A. Knowles, Denver, Colo.

Application-May 2,1, 1948,1"Serial-No;28;482

2 iGlaims.

This invention relates to improvements in bits of the type employed in connection with rock drilling. 1 i

Wherever mining 'or tunnelingds carried-on, as

-well asin many other placesflit'becomes necessary to drill rocks for use in connection with blastingand for many other-purposes. "Thesimplestdormofrock drill is made :from a steel bar sharpened to a chisel point, or :pro- :vided with crossed cutting edges, which are sharpened and flattened seas to .facilitate the cuttingandipenetration of the rock.

Since'the discovery of extra ghard metals such :tungsten :carbide, drill bits have been con structed in -such away thatthe cutting tips or :e'dgesare made-gfromrthis metal.

'It is the object of :this invention to .produce atrock d-rill having "a removable bill which tea-n be made from extra. hard steel orirom tungsten carbide or :a-ny other :metal that may be found suitable, and it shall be so constructed that it can be readily-removed and replaced whenever necessary;

A further object of the invention-is to produce a drill it of such construction that the drill steel can'be fo'rmedto the desired shape with the least possible expense :and with the greatest degree. of; accuracy.

l-he above and anyotherrobjects of theinvention thati-may appearas the description iproceeds are 'attained by means of 1a .rconstructionrand an arrangement of parts that will now be described in detail and for this purpose, reference will be had -to the accompanying-drawing inwhich the invention has been ill-ustrated',- and in which:

Figure 1 is aside elevation showing a section of drillsteel provided-with aremovabl'e 'bit-constructed in accordance with this invention;

Figure 2 is a side elevation taken at right angles to that shown in Figure 1;

Figure 3 is a view showing a portion of the drill steel and the bit in cross section and a portion of the steel in elevation;

Figure 4 is a cross section taken on line 4-4, Figures 1, 2 and 3;

Figure 5 is a top plan view looking through plane 5-5, Figure 2;

Figure 6 is a top plan view looking through plane 6--6, Figure 7;

Figure 7 is a side elevation, partially in section, similar to that shown in Figure 3;

Figure 8 is a side elevation looking through plane 8-8, Figure 9; and

Figure 9 is an end view of the drill shown in Figure 8.

has been indicated by brokenlines. :sten carbide is-employed, the drill bit'is usually constructed-in the manner :shown in Figure '6,

leaves "two outwardly tapering surfaces H and which also forms adiametrical cut All-extending the wholewidth of the drillsteel.

' The drill bitwhich forms part-oi this invention maybemade from very hard tool steel or from tungsten carbide or from any other material thatmay be found-to besuitable. Such:drill bits must,xof course,*be very hard and have sufiicient strength to prevent them "from accidentally 'breakingduring operation.

The drillwbit which is shown in the. drawing consists of a bar IQ of a width andtdepthi'to fit '-'the--diametrical cut 18. The outer edge'of :bar

19* is wedge-shaped and tapers to aipoint 20,

which is usually slightly-rounded and forms the cutting edge. "bar are to arcuateportionszl whose :inner sur- -faces are curved in such a=way-as to fit the outer Extending from the ends .of the surface of the drill steel as shown in Figurefi.

The connecting members 2 lare lfl-attened along the sides asiindicated at 212. Thisprovides passages 123 between the drill and the wall of the drillhole, .(Figures 5, 6:and:9),3for the :escape of water,:ai-r.and rock during the operation.

In Figures 5 and 6 the outline of the drill hole When tungbut if the drill bit is made from steel, the sides 2|, instead of extending from one end of the bar to the other, may be formed from shorter portions like those designated by reference numeral Zla in Figures 2, 4 and 5. When the construction shown in Figures 4 and 5, for example, is employed, a greater space or opening is provided for the escape of crushed stone, water and air than when the construction shown in Figure 6 is used. The construction shown in Figures 4 and 5 may, of course, be employed in connection with tungsten carbide, if desired.

The drill bit i made in such a wa that it fits the drill steel quite snugly and after it has been positioned on the drill steel, it is connected with it by some suitable solder or it may be brazed to the drill steel or connected thereto in any other suit- 3 able manner. It is, of course, desirable and necessary that the drill bit shall be fastened to the drill steel as securely as possible and this is usually accomplished by sweating or soldering. The solder is selected in such a way that it will melt at a temperature that will not damage the drill steel and the drill bit may, therefore, be removed and replaced without requiring the drill steel to be heated to a temperature that will damage it. The curved sides 2i and Zla have their front edges inclined so as to lie in planes parallel to the planes of inclined surfaces I1 and.

are preferably positioned slightl below the outer edge of the inclined surfaces, as shown in Figures -2 and 3. The center or cutting bar l9 projects slightly beyond the edge of the sides I! so as to the drill steel. When a chisel type drill bit is employed, the end of the drill steel can be quickly and readily made into the proper shape by a milling cutter, thus assuring that all of the drill steels will be identical and reducing the cost of manufacture. Where several cutting edges are used and separate pieces of tungsten carbide introduced into each, the work and expense of preparing the drill is greater than with the construction shownhere. 'Thecutting bar is readily accessible to sharpening, if this should become necessary. When a construction like that shown in Figures 8 and 9 is used, it is very difficult to 1 sharpen the cutting bars.

permit it to wear to some extent before getting into coplanar alignment with the wedge surfaces.

As has already been pointed out, the axial open ing IS in the drill steel is employed for introducing water or water and air, or air alone into the drill hole so as to remove the rock dustformed by the drilling. In the construction shown in Figure 3, the outer end of hole l6 has been bored to a slightly larger diameter, as indicated at 24. This leaves segment-shaped openings 25 on opposite sides of cutting bar I!) through which the water or air may enter. The dust, as well as the water or air, returns through passages 23 which are clearly shown in Figures 5, Sand 9. -With the construction shown in Figures -2 and 3, the center portion of cutting bar I9 is left unsupported, which is sometimes objectionable, and wherever such construction is not desired; the width of opening I8 is made of the diameter of opening it so that the cutting bar will fit snugly against the sides of the opening, the whole diameter of the steel. When so constructed the braning or soldering is continuous over the whole length of the cutting bar. With the construction shown in Figure 7, the air or water exits through openings 26. i v

A chisel cutting edge like that shown in Figures 1 to 7, inclusive, is believed to be preferable to the cross cutting edges shown in Figures 8 and 9, but, if for any reason a construction like that shown in Figures 8 and 9 is desired, the drillbits may readily be made so as to provide such a construction.

With the construction shown in Figure 9,there are two diametrical cuts I81; and two cross bars I911 connected by portions Zlb. It will be noted that the parts 2Ib are substantially straight, leaving escape passages 23, of which four are shown. 1

Attention is called to the fact that with the above construction the drill bit is formed from a single piece and can be very quickly positioned on What is claimed as new is: 1. A rock drill comprising, a tubular drill steel ,having its point inclined from opposite sides to form a wedge, the wedge-shaped end having a diametrical cut in the plane bisecting the angle of the wedge, and a hard bit having a bar positioned in the cut, projecting beyond the line of intersection of the planes of the wedge sides, the ends of the bit bar having arcuate extensions embracing the drill steel, the end edges of said extensions lying in planes substantially coincident with the corresponding wedge surfaces of the bar.

2. A rock drill comprising a tubular drill steel having one end wedge-shape, and provided with a diametrical cut parallel with the bisector plane of the wedge angle, and a bit of hard material comprising a bar of a thickness equal to the width of the cut, and a length equal to the diameter of the bar, positioned in the cut, the outer edge being transversely wedge-shape, the ends of the bar terminating in arcuate portions embracing the outer surface of the drill steel, the outer edges of the drill steel embracing portions being substantially parallel with the planes'of the wedge surfaces.

SILAS A. KNOWLES.

REFERENCES CITED The following references are of recordin the file of this patent:

UNITED STATES PATENTS Date France Sept. 14, 1936 

